My car is backfiring but it only does it above 50 mph. When I'm deaclerating above 50, it will pop a few times, then once the torque convertor unlocks, it will let out a quiet backfire and not backfire until I get above 50. It is also louder in 3rd than in 4th. I know once my friends said they saw flames shoot out my exhaust pipes before.

 

When i let off the gas fast it will pop out the exhaust which is normal for my car. I am not sure if you have problems but if it only does it during deceleration you should be ok. As for the flames i don't tkink that normal.

 

Is the car running rich at all? Any SES light present? How is the condition of the plugs, wires, and coil?